Composite stock for machine-knives and method of making the same.



F. SEARLE.

COMPOSITE STOCK FOR MACHINE KNIVES AND METHOD OF MAKING THE SAME.APPLICATION FILED MAY 7,1908.

v9295, 661 Patented June 22, 1909.

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- Z/L/iZ 2125525- UNrTED STATES PATENT oFFIoE.

FREDERICK SEARIiE, OF WORCESTER, MASSACHUSETTS, ASSIGNOR TO COES WRENCHCOMPANY, WORCESTER, MASSACHUSETTS, A CORPORATION OF-MASSACHUSETTS.

COMPOSITE STOCK FOR'MACHINE-KNIVES AND METHOD QF I VEAKING- THE SAME.

Specification of Letters Patent. 7' Patented June 22, 1909.

Application filed May 7, 1908. Serial No. 431,331.

T all whom it may concern:

Be it known that I, FREDERICK SEARLE, a citizen of. the United States,residing at Worcester, in the county of Worcester and State ofMassachusetts, have invented a new and useful Composite Stock forMachine- Knives and Method of Making the Same, of which the following isa specification, reference being made therein to the accompanyingdrawings.

The object of my present invention is the production. of a securelywelded composite stock for machine knives of the double edgedchannel-bar pattern, more especially for the ledger knives for lawnmowers, or similar knives having two turnedup edges. Also, to provide aconveniently workable process whereby a double edged channel-barknifestock can be successfully and economically manufactured, and thesteel edging material efficiently affixed to the body or backinga'V-welded integration; and to practically produce a composite stock ofsuch character that the dual cutting-edges of knives made therefrom canbe properly hardened and tempered without destroying the capacity of theproduct for beingstraightened or fitted after the knife is formed, orwhile being formed therefrom; thereby afiording more perfect andstronger knives of the pattern s ecified than heretofore produced. These0 jects I attain by the means hereinafter explained, and illustrated inthe drawings,wherein Figure 1 represents a cross section of the iron andsteel members as primarily assembled in the fagot. Fig. 2-re resentsacross section of the billet after going through the first reductionpass. Figs. 3 and 4 represent successive cross section shapes of thecomposite bar after going through the second and third reduction passesrespectively. Fig. 5 represents a cross section of the completed stockas it is issued from'the final pass of the reduction rolls; and Fig. 6is a front view of a pair of reducing rolls having passes formed forproducing composite knife-stock in accordance with my invention.

In a machine knife of the channel-bar shape it is desirable that theupturned lips, whereon the cutting edges are formed, should be hardenedand tempered, while the bar as a whole should be strong and rigid, butat the permit of the knife made therefrom being straightened or fitted,to eliminate the warpings and distortions incident to thehardenalinement of the opposite edges. It is also essential that thelips or upturned edges be of such quality and texturethat they can beground away, by successive sharpenings, guite or nearly to the bottomplate or backing. course give good cutting edges, but an allsteel stock,when hardened to the requlred degree, cannot be successfullystraightened and adjusted by bending; and furthermore an all-steel stockis comparatively expensive and may not be produced with the requisiteeconomy.

To produce composite stock of the shape specified and'having therequisite quallties, and that can be manufactured with ractical economyand success, my improve process is as follows: I prepare a fagot(Fig. 1) of the desired length, composed of a rectangular sectioned barI of refined wrought iron, or soft steel (of ten per cent. carbon orless) of a dimension say three-fourths inch by one and three fourthsinches, more or less, and two rectangular sectioned bars S of cruciblecaststeel ortool-steel, of. a dimension say one which latter are placedflatwise against the o posite edges 12 of the bodybard, with t eirrespective edges 13 projectlng n either direction beyond the flat facesof sa d bodybar, as illustrated in Fig. 1 1n which form the members,previously heated and fluxed,

adjacent surfaces sufliciently to keep .the members together in place.when properly heated, is run through a pair of reducing rolls A, B, in apass 1 hav ngan approximately straight top and bottom, and rounded orinclined ends that compress the exterior angles'of the billet and firmlyweld the steel members to the opposl te edges of the body-bar, reducedas at 1 w1t h a somewhat crescentic shaped cross-sect on, as at Sforming an overthrust of the upper and lower edges of the steel at theweld oint 5, as indicated in Fig. 2. The composite billet 1s l thenfurther reduced in a pass 2, the form of same time sufficiently toughandbendable to j ing operations, or to" properly adjust the inch by fivesixteenths inch, more or less,

are hammer-welded to primarily unite their This fagot,

i which presents a fiat at one side and a double channeled contour atthe opposite side;

" V-shaped i "the top edges andv outer faces of the upstandwhereby thebillet is given the s ape approximately as shown in Fig. 3, theintermedial portion I being reduced to about one half the thickness ofthe side portions S which latter are crowded inward at the corners 6.The bar is next inverted and put through a reducing pass 3 that flattensthe body or backing portion nearly to its final thickness, as at 1 andtransforms the edge portions into embryo upturned lips, as at S, forcingthe lines of the welding into oppositely directed bird-mouth or V-shapedcontour, as at 7, but leavin a proportional excess of thickness at theshoulder 8; the stock then having the shape approximately as indicatedin when thus shaped is put through a final pass 4 of the rolls, wherebyit is slightly reduced in its full width, the body portion flattened orfurther reduced to finished dimension for the backing, as at I, and theexcess at the shoulders 8 reduced in thickness and forced upward makingthe upturned lips S at each edge, complete and of approximately uniformthickness therewith; and disposing the welding along the angle or baseof the lips in such manner that the upstanding lips are substantiallyall hard steel, while the backing or body web is of iron ornon-hardening material, as shown in Fig. 5. Thus roducing a firmlyunited composite stoc of channel-bar-section, with edges that can behardened and tempered, and with a body that will permit of thestraightening, twisting, or readjustment of the alinement of the knifeafter it has been tempered, and with the V-welds of the steel-edgeoverlap ing onto the softer material approximately a ong the angles, asat 9, in a manner that will avoid liablitiy of rupture in the weld inthe process of manufacture; the stock presenting 3rd and efiicientupstanding lips along both e ges.

The class of machine knives for whichthis improved composite stock isproduced, and for which itis peculiarly adapted, are the ledger-knivesfor lawnmowers and similar mechanisms, wherein a spirally bladedrevolver is arranged to shear against astraight ledger knife. Thefinished knife made. from this cutter-stock is of approximately the samecross-section as that of the complete stock, as shown in Fig. 5; theknife being a piece of the stock of the required length,

suitably hardened andLtempered, and having ing lips simply ground, onthe lines f and t, for giving the desired cutting .edges, and which canbe re-ground and used until the entire upstanding lips are worn away,with-' out exhausting the qualityof the stock.

I am aware that a channel-bar shaped cutter stock of a non-compositenature has here- Fig. 4. The bar' tofore been employed, and I do not,therefore, herein broadly claim that shape, per se,

as applied to cutters; but so far as I am turing of such formedcomposite knife-stock,

prior to my invention hereinbefore set forth.

What I claim and desire to secure by Letters Patent, is-

1. The method of making double-lipped composite knife-stock, whichconsists in aplyingto each of the two edges of a rectanguar bar ofwrought iron a bar of cast or toolsteel of greater width than thethickness of the iron, condensing this composite fagot to weld and formthe steel in approximately crescent shape upon the res ective edges ofthe body-bar, reducing said bar with an excess of reduction centrallyalong one side; further reducing the same in channel-bar shape to formembryo lips of the steel having an excess of thickness at the shoulderswhere the welds embrace the edges of the iron, then rolling said reducedbar into its final doublelipped shape with the mass of disposed in thelips, and the welding hne along the base of the lip, substantially asset forth.

2. The improvement in the method of making composite stock fordual-edged ma steel chiefly f chine knives of the character specified,which consists in combining in a fagot, a rectangular sectional body-barof iron or soft steel and.

two bars of crucible cast or tool steel respectively arranged withprojecting edges upon the opposite edges of said body-bar, marilyuniting the same by hammer-weld ng, and at an initial rollingcompressing the exterior projecting edges of the billet inwardso as tooverthrustthe steel edgings in opposite crescentic form upon the bodyportion, then reducing the. body thickness, and by successive stagessubsequently forcing the steel edgings into the form of u standing lipsat the respective edges, and c osing the welding lines into inwardlyover-lapping bird-mouth or V -shaped integrations a ong the op ositeedges of the backing body, substantia ly as set forth.

3. A composite stock for machine-kmves of channel-bar cross-section,said stock comprising an a proximately flat body-portion consisting 0soft non-hardenable steel or wrought-iron, and offset upstandinglongitudinal lips consisting of hardenable steel or tool-steel alongeach edge'of said body, the

body and lip portions being integrally united by'o ositely disposedV-shaped'weldings. longiififdinally along the junction line of the lipand body, as set forth.

4. The within described double-edged cqmlposite stock formachine-knives, said at the angle or up-turn-ofiset of the-respem 10stoc comprising a flat non-hardenable centive lips, substantially as setforth. tral body-strip, in combination with an up- Witness my hand thisfourth day of May standing outwardly inclined li of harden- 1908.

able steel uniformly a plied t ereto along FREDERICK SEARLE each of theedges, said ips being of approximately the same thickness as thebody-strip, Witnesses: Q

and integrally united longitudinally there- 7 CHAS. H. BURLEIGH, with byoppositely disposed weldings located ELLA P. BLENUS.

